Opacity as integer not float

I could not get the plugin to work and decided to debug, why that happens:

In default configuration, you define opacity as `opacity=0.35`. Parsing this fails, if your NumberDecimalSeparator is anything but a dot (which happens to be the case in if you're estonian ..)

Here be one of the possible solutions, to use integers in the range of 0..100 in favour of doubles in 0.0..1.0.

Another possible solution (if you do not want to mess with the guys with customized configuration file, who want to update the plugin), is to wrap the opacity setter around a try/catch and revert to 0.35 if the parsing fails. Which of course might raise further questions, as to why their opacity settings are not working :)

Then again try/catching and reverting to default for faulty configurations might still be somewhat worth it, otherwise they just see a broken (doing nothing) extension.